Within the scope of the present invention, a mixed-light LED is understood to mean a component that comprises at least one LED chip and one conversion element, wherein the conversion element converts light emitted by the LED chip into light having a different, generally a greater wavelength. By means of the simultaneous perception of the light emitted by the LED chip and the light converted by the conversion element, the impression of mixed-color light is produced.
Such mixed-light LEDs are frequently configured as white-light LEDs. In this connection, a luminous substance is excited by means of an LED chip that emits in the blue spectral range; this substance in turn emits light in the yellow-orange spectral range. The mixture of blue and yellow-orange light is perceived as white light.
However, the spectrum of such a white-light LED clearly differs from a conventional white-light source such as an incandescent bulb, for example, since a conventional white-light source has a rather broad spectral distribution, which covers large parts of the visible spectral range, while a white-light LED of the type described above primarily shows blue and yellow-orange spectral components. This difference is particularly noticeable in connection with the different color reproduction of a white-light LED, on the one hand, and a conventional white-light source such as an incandescent bulb, on the other hand.
An improvement of the color reproduction can be achieved in that in the case of an LED module, both white-light LEDs and color LEDs are used, wherein the color LEDs supplement the spectral components that are missing in the spectrum of the white-light LEDs.
In similar manner, it can also be necessary, in the case of other non-white mixed-light LEDs having a conversion element, to supplement missing spectral components. However, here it is less the color reproduction than the desired exact color location that stands in the foreground. It is fundamentally possible to implement a predetermined color location of the mixed-color light generated by a mixed-light LED, by means of suitable coordination and mixing of luminous substances. However, the effort and expense for this is relatively great, since a special casting mass containing the corresponding luminous substances generally has to be produced and processed. In the automated production of large numbers of LEDs, in particular, this method of procedure is disadvantageous for economic reasons.